There are several ways to add an application to the panel:
Perhaps the easiest method is to use the entry Panel->Add application in the panel menu (the menu that appears when pressing the K button on the panel). The menu shows all installed KDE applications. To add a button to the menu, simply click on the application.
You can also simply drag a .desktop file from a window of the file manager to the panel.
On some Red Hat® systems, the clock in the panel always shows the time in GMT. This is a bug in the Red Hat® setup. To solve it, just create this symbolic link: ln -s /usr/share/zoneinfo /usr/lib/zoneinfo.
Yes. Try starting it with something like this: kpanel -no-KDE-compliant-window-manager.
Look for $HOME/.kde/share/apps/kpanel/pics/go.xpm and $HOME/.kde/share/apps/kpanel/pics/mini/go.xpm and replace them. Do not forget to flatten the replacements to one layer, or else you will not see anything. Create the directories if they do not already exist. Then restart kpanel.
Look for $HOME/.kde/share/apps/kicker/pics/go.png and $HOME/.kde/share/apps/kicker/pics/mini/go.png and replace them. Do not forget to flatten the replacements to one layer, or else you will not see anything. Create the directories if they do not already exist. Then restart Kicker.
You can't if you are using KDE 2 final. It is now implemented in the current CVS snapshot, though. Read more about it at http://dot.kde.org/972916165.